Research Progress Report 397
November, 1971

Economic Analyses of Nitrogen-Fertilized Orchardgrass and Smooth Bromegrass
F. T. Abbring, R. W. Taylor, C. L. Rhykerd and C. H. Noller
Departments of Agronomy, Agricultural Economics and Animal Sciences

SUMMARY
The use of nitrogen fertilizer increased the crude protein content of orchardgrass and smooth bromegrass, and increased total yield up to levels of 400 to 500 pounds of nitrogen per acre. By increasing the nitrogen level, the nutritive value per ton of forage was also increased; but at the highest nitrogen level, the production costs increased faster than the value of the forage produced. Likewise, as the number of harvests increased, so did the value per ton forage; but final harvest yields were so low that the value of the forage produced per acre raised a question as to whether the last harvest is economical.
This research indicated that the use of 500 pounds of nitrogen per acre on orchard-grass was more profitable than either 250 or 1000 pounds per acre. Similarly, 400 pounds of nitrogen per acre on smooth bromegrass was more profitable than either 200 or 800 pounds. Further research is required to define more precisely the most profitable rate of nitrogen.
Additional research is also needed to determine the most profitable number of cuttings. Number of cuttings affects the cost of harvesting, the quantity of forage harvest-
ed and the nutritive value of the harvested forage. Thus, a compromise must be made between production costs and value of the forage harvested in order to obtain the highest net return per acre.

PROCEDURE
This report presents an economic analysis of data from forage research reported partially in Purdue Extension publication AY-176. The orchardgrass and smooth bromegrass used in this study were grown in 1967 and 1968 on a highly productive soil (Chalmers silty clay loam) at the Purdue University Agronomy Farm. The plots were fertilized with 200 pounds of phosphorus and 600 pounds of potassium per acre per year. Nitrogen, as a split application, was applied each year at the annual rates shown in Tables 1 and 4.
In order to calculate the value of a forage on an acre basis, its yield, protein content and total digestible nutrient (TDN) content were considered. A basic assumption made was that the TDN and protein in forage will substitute for the TDN and protein in corn grain and soybean meal when fed in a complete balanced ration. Previous research at Purdue showed that high quality alfalfa was competitive with corn silage in dairy rations

PURDUE UNIVERSITY • Agricultural Experiment Station • Lafayette, Indiana